MRI scanners, which are used in various fields such as medical diagnostics, typically use a computer to create images based on the operation of a magnet, a gradient coil assembly, and a radio frequency coil(s). The magnet creates a uniform main magnetic field that makes nuclei, such as hydrogen atomic nuclei, responsive to radio frequency excitation. The gradient coil assembly imposes a series of pulsed, spatial-gradient magnetic fields upon the main magnetic field to give each point in the imaging volume a spatial identity corresponding to its unique set of magnetic fields during the imaging pulse sequence. The radio frequency coil creates an excitation frequency pulse that temporarily creates an oscillating transverse magnetization that is detected by the radio frequency coil and used by the computer to create the image. An image may be created using one of many known reconstruction techniques. Typically, in a cylindrical MRI system, there is a radio frequency coil and a gradient coil assembly within the magnet.
During a patient scan, the gradient coil(s) of the gradient coil assembly that produce the magnetic field gradients dissipate large amounts of heat. The heat produced by the gradient coils may be removed from the gradient assembly by liquid filled cooling tubes positioned at a given distance from the heat conductors. A liquid coolant, such as water, ethylene or a propylene glycol mixture, absorbs heat from the gradient coils as it is pumped through the cooling tubes and transports the heat to a remote heat exchange/water chiller. Heat is then ejected to the atmosphere by way of the heat exchange/chiller.
With modem high power MRI imaging sequences, however, it is increasingly difficult to remove the heat generated by the gradient coils. This, in turn, increases the risk of MRI patients becoming over-heated. Therefore, there is a need to provide additional cooling to gradient coils in an MRI scanner. In particular, there is a need to provide an apparatus and method for providing forced-air cooling to a gradient coil. It would be advantageous to provide an apparatus and method to provide forced airflow to a surface of a gradient coil to cool the gradient coil. The forced air-cooling may be provided by itself or in addition to a liquid cooling system or other cooling system.